Background: Many cancer patients who require external beam radiotherapy such as breast cancer patients, present with irregular surface topographies and tissue inhomogenieties in the treatment field. Such irregularities give rise to unacceptable dose non-uniformity. Standard fields cannot be applied without compensation for missing tissue. 1-D and 2-D missing tissue compensators can be used but they have limitations. 3-D compensators are the most effective but they are normally fabricated using very expensive automated systems. Objectives: To study the variation of linear attenuation coefficients of different materials in megavoltage photon beams, select a tissue equivalent compensating material and commission a local 3-D manual missing tissue compensator cutter. Methods and materials: Linear attenuation coefficients were measured for tin, River sand mix, Lincolnshire bolus and dental modelling wax for different energy megavoltage photon beams. Measurements were done in a water phantom using a cylindrical ionisation chamber at varying depths. The CT numbers and densities of the materials were also measured. Negative plaster of paris moulds of the breast and head and neck areas were made using a RANDOTM Alderson anthropomorphic phantom from typically simulated fields. 3-D missing tissue compensators were then fabricated on the manual cutter and were tested for their effectiveness during treatment delivery. Results: Linear attenuation coefficients were dependent on photon beam energy, the thickness and density of the attenuator, but independent of the depth of measurement for compensator thickness of more than 2 cm. Lincolnshire bolus and dental modelling wax with CT numbers of –78 ± 9 and -88 ± 18 and densities of 1.4 ± 0.0 g/cm3 and 0.9 ± 0.0 g/cm3 respectively can be regarded as tissue equivalent materials. The fabricated 3-D missing tissue compensators were effective in correcting for dose non-uniformities compared to fields with no beam-modifying devices or wedges (1-D compensators). Conclusions: The 3-D missing tissue compensators were effective in correcting for dose non-uniformities in treatment fields involving very irregular surface topographies compared to 1-D and 2-D methods. They can be fabricated cheaply using a 3-D manual missing tissue compensator cutter. Quality control procedures need to be followed during fabrication.

The purpose of this thesis is to describe the three-dimensional velocity flow field measurements in the vicinity of the inlet mouth of a cutterhead suction dredge. Using acoustic Doppler velocimeters (ADVs), an accurate visualization of the velocity flow field was used to determine the region of influence around the cutterhead. Similitude is used in the experimental study to determine the correlation between the velocity flow field and other dredge parameters such as suction intake diameter without the cutterhead and with a rotating cutterhead. This is useful to the dredging community for two reasons: first, knowing the region of influence around the cutterhead helps the dredger achieve higher production by using a more efficient cutting depth and second, achieving similitude with the velocity flow field allows for more accurate model testing in the future. In order to help understand the more complex flow field around the cutterhead created by the cutting process, scenarios involving three different suction flow rates, three cutterhead rotation speeds, and two swing speeds, were investigated. Prior studies of the flow field around the cutterhead provided a means to predict the velocity at the cutterhead intake. The flow field studies herein provide an extension into three dimensions as well as a verification of the previous results. The highest velocities were found to occur nearest the cutterhead, specifically in the lower hemisphere of the cutterhead where the suction intake is located. The magnitude of these values greatly decreased with increasing distance from the cutterhead. In addition, the flow rate is shown to directly correlate to the velocity around the cutterhead. It was found that the region of influence was nearly symmetrical around the cutterhead, but the shape could more accurately be described as an ellipsoid. The volumes of the regions of influence ranged from 10 ft^3 (0.283 m^3) to 80 ft^3 (2.27 m^3) for the model dredge and from 2,250 ft^3 (63.70 m^3) to 17,000 ft^3 (481.40 m^3).

Cutter Soil Mixing (CSM) is a recently developed deep mixing technique that has grown to include the treatment of sandy and silty soils. This study seeks to investigate the influence of (i) sand-silt ratio, (ii) cement content, (iii) water content and (iv) time on the unconfined compressive strength of saturated cement-treated soil specimens. A new test device and method of specimen reconstitution were conceived in order to obtain a saturated mix of soil and cement. A comparison of results show strength increases non-linearly to decreasing total water-cement ratio, and that this trend is largely independent of sand-silt ratio. Furthermore, strength increases non-linearly with time and is independent of sand-silt ratio. Lastly, it is recommended that the strength be correlated with total water-cement ratio rather than cement content, in order to improve data reporting and provide design guidance to engineering practice.

The technology of multi-axis machining has been applied extensively to the manufacturing of dies, molds, and various aerospace components. For machining mechanical parts with complex, sculptured surfaces, the use of multi-axis machine tools is probably the only one solution for avoiding tool-part collision during machining. Since cutting force will be changed by cutter attitudes, the machined surface characteristic can also be affected by cutter attitudes. In this thesis, the major concern is focused on investigating the effect of the cutter attitude on machined surface roughness. Based on the relationship between the cutter incline angle and the enveloped condition in cutting, the correlation of the mean chip thickness and the cutter incline angle is observed. To identify the relationship between the cutter attitude and the workpiece surface roughness, experimental verification is performed by milling aluminum alloy material. By fixing the cutting depths and the width of tool paths, different spindle rotational speeds and cutter incline angles are taken to machine the workpieces. And then, the machined surfaces are measured for their surface roughness. Form the experimental results, it shows that the surface roughness will reach a peak value at a special cutter incline angle. The tendency between the surface roughness and the incline angle agrees with that between the mean chip thickness and the cutter attitude approximately.

Cutter Soil Mixing (CSM) is a recently developed deep mixing technique that has grown to include the treatment of sandy and silty soils. This study seeks to investigate the influence of (i) sand-silt ratio, (ii) cement content, (iii) water content and (iv) time on the unconfined compressive strength of saturated cement-treated soil specimens. A new test device and method of specimen reconstitution were conceived in order to obtain a saturated mix of soil and cement. A comparison of results show strength increases non-linearly to decreasing total water-cement ratio, and that this trend is largely independent of sand-silt ratio. Furthermore, strength increases non-linearly with time and is independent of sand-silt ratio. Lastly, it is recommended that the strength be correlated with total water-cement ratio rather than cement content, in order to improve data reporting and provide design guidance to engineering practice.

Cutter Soil Mixing (CSM) is a recently developed deep mixing technique that has grown to include the treatment of sandy and silty soils. This study seeks to investigate the influence of (i) sand-silt ratio, (ii) cement content, (iii) water content and (iv) time on the unconfined compressive strength of saturated cement-treated soil specimens. A new test device and method of specimen reconstitution were conceived in order to obtain a saturated mix of soil and cement. A comparison of results show strength increases non-linearly to decreasing total water-cement ratio, and that this trend is largely independent of sand-silt ratio. Furthermore, strength increases non-linearly with time and is independent of sand-silt ratio. Lastly, it is recommended that the strength be correlated with total water-cement ratio rather than cement content, in order to improve data reporting and provide design guidance to engineering practice. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

This Master's thesis project was provided by Epiroc Rock Drills AB and conducted at Camatec Industriteknik AB in Karlstad, Sweden. The project is centered around the cutter wheel in the mechanical rock excavator Mobile Miner 40V.  This cutter wheel is equipped with cutter discs that grind rock into debris as the wheel rotates and thrusts forward. The internal system consisting of a bearing constellation and the components in its vicinity has experienced a certain degree of wear in the form of scuffing and this was detected on the surfaces of some of the components in the system. The reasons for this occurrence are unknown and per the request of the thesis provider, this was to be determined. The thesis provider also requested a new Finite Element Analysis (FEA) model of the system along with feasible load cases that can be applied to said model. The project was deemed extensive and was therefore decided to be conducted by two students. This thesis covers the determination of the load cases as well as the optimization of the current design of the system inside the cutter wheel. During the pre-study, relevant background data was obtained for the cutter wheel and the internal system. Methods and models considered to potentially be useful were also gathered. The system in question was divided into two separate models; one consisted of a tribo-system with two components in sliding contact and the other consisted of the bearing constellation along with the outer-most section of the cutter wheel. The purpose of the first model was to use it to determine the contact pressure between the tribo-surfaces and by doing so, be able to determine the expected lubrication regime for the oil in the tribo-system. A material selection process was also conducted on the tribo-surface that had experienced the most severe surface damage. Additionally, minor reconstructions were made with the purpose of optimizing the system. The purpose of the second model was to apply the calculated load cases to the cutter disc attachments located on the outer-most section of the cutter wheel and then determine the contact pressures that develop on the bearing roller elements. The results of the thesis work consist of five potential material options, two reconstructions and 60 different load cases for the FEA model. With the load cases, the largest contact pressures on the bearing roller elements was determined. In addition, the cause of the severe surface damage that had occurred in the system is believed to have been identified. Further work on the project work is believed to be required. Future work of interest are determining load cases that incorporate multiple cutter discs simultaneously in contact with the rock, reconstruction solutions for the oil inlet and outlet pipes, a more thorough materials selection process and a criterion for the expected lubrication regime in the tribo-system based on tests performed with materials that are more identical to the ones in this project. / Detta examensarbete tillhandahölls av Epiroc Rock Drills AB och genomfördes hos Camatec Industriteknik i Karlstad, Sverige. Projektet är centrerat kring cutterhjulet i maskinen Mobile Miner 40V som är avsedd för mekanisk bergavverkning. Cutterhjulet är utrustat med cutter discar som maler berget till mindre flisor genom att hjulet roterar och trycks framåt. Det inre systemet bestående av en lagring med närliggande komponenter har utsatts för en viss grad av nötning i form av scuffing och detta upptäcktes på ytorna hos vissa av komponenterna i systemet. De bakomliggande anledningarna för denna förekomst är okända och utifrån begäran från projektgivaren skulle dessa anledningar fastställas. Projektgivaren eftersökte även en ny FEM-modell av systemet tillsammans med rimliga lastfall som ska kunna appliceras på modellen i fråga. Projektet ansågs tämligen omfattande och det bedömdes därför att två studenter krävdes för att genomföra arbetet. Denna uppsats behandlar framtagningen av lastfallen såväl som optimeringen av den nuvarande designen av systemet inuti cutterhjulet. Under förstudien hämtades relevant bakgrundsdata för cutterhjulet och det interna systemet. Metoder och teorier som ansågs vara potentiellt användbara samlades även in. Systemet i fråga delades in i två separata modeller; en bestod av ett tribo-system bestående av två tribo-ytor i glidande kontakt och den andra bestod av lagringen tillsammans med den yttersta sektionen hos cutterhjulet. Syftet med den förstnämnda modellen var att använda den för att bestämma kontakttrycket mellan tribo-ytorna, och genom detta kunna fastställa den förväntade smörjningsregimen hos oljan i tribo-systemet. En materialvalsprocess utfördes även för tribo-ytan som hade utsatts för den mest allvarliga skadan. Även smärre omkonstruktioner utfördes med syftet att optimera systemet. Syftet hos den andra modellen var att kunna applicera de beräknade lastfallen på cutter discarnas infästningar som återfinns i den yttersta sektionen hos cutterhjulet och sedan bestämma kontakttrycken som uppstår på rullarna i lagren. Resultaten från arbetet består av fem potentiella materialval, två konstruktionsändringar och 60 olika lastfall för FEM-modellen. Genom att applicera lastfallen bestämdes de största kontakttrycken på lagrens rullar. Utöver detta anses det att anledningen för den allvarliga ytskadan som hade skett i systemet har identifierats. Det anses att fortsatt arbete krävs för projektet. Kompletterande arbete som anses vara av intresse är lastfall som inkluderar flera cutter discar i ingrepp samtidigt med berget, konstruktionslösningar för tillförsel och bortförsel av oljan, en mer djupgående materialvalsprocess och ett kriterium för förväntad smörjningsregim hos tribo-systemet baserat på tester utförda med material som är mer identiska med dem som förekommer i projektet.

The area of this work is distressed denim in women’s wear. Denim wear has been distressed by machines to imitate the individual patina that becomes from wearing e.g. a pair of unwashed jeans until the color strips from creases. This work uses challenges the faked used look, using a decorative motive in distressed denim. Lace has been used as a decoration of dress since medieval times. By using lace as the pattern for the distressing of denim one will decorate the denim in a destructive way that questions the perfection and delicate way that lace is usually used. Lace consists of threads and holes that builds an ornamental pattern, worn down denim often results in holes and threads at the most vulnerable areas of the garment. Denim is a warp faced cotton twill weave with blue indigo yarn in warp and natural white yarn in weft. By using a laser cutter to engrave a pattern on the warp faced side of the denim, one can set the settings on the laser cutter so that only the blue warp threads will be met by the laser beam. After wash the engraved warp threads will dissolve and depending on the scale and the design of the pattern the unengraved parts can dissolve as well. Therefor one needs to fix the unengraved parts of the pattern before wash if one wants the pattern to remain. There is several ways to fix the pattern before wash; this work includes fixing with laser cut fusing and with seams. Some of the garments aren’t engraved in this work but cut in the laser cutter. The two cutting techniques used is first a regular cut out technique and second a slicing technique. The shapes of the garments derives from typical denim and lace garments such as jeans, denim jackets, denim shirts, lace gown, wedding dresses and underwear such as negligees, corsets, bras and panties. Initially, experiments were done to understand the visual and technical effect of clashing materials and garments. The result is a collection, combining ideas from two different origins in fashion, denim from mineworkers and lace from nobles. The outfits manages how one can control distressed denim and shows a variation from lace, to garments where the traces of lace have completely or partially dissolved. The primary motive is to investigate surface possibilities in distressed denim through a specific pattern. The result is difficult to control and experiments in full scale are necessary to evaluate distressed experiments. The secondary motive is global. Can lasercutting and engravings be an alternative to sandblasting ? It is not dealt with in this investigation. However this investigation shows a selection of alternative expressions for distressed denim. This work challenges the idea of distressed denim as the only way to make a fake, torned effect. It points at new possibilities, using decorative motifs by lasercuts and engravings in combination with other treatments in search for alternative expressions in denimwear.

The aim of the work was to verify the performance and design working quality performance of rotary milling machines with horizontal axis of rotation in artificial forest regeneration, support of natural forest regeneration in selected forest stands and in agriculture with different soil and terrain conditions. The measurement was carried out on four different carrier cutters, each machine carrying a different soil milling machine. Measurements took place in various environments as well as soil types, crops or quality requirements for the work performed. In this work are compared performance of given carriers, in terms of aggregation with individual models of milling machines. The tables show the most important parameters such as average fuel consumption, average area efficiency and fuel consumption to area efficiency. Furthermore, there is an evaluation of the quality of the work done.

Tese de mestrado integrado. Engenharia Civil (Especialização em Geotecnia). Faculdade de Engenharia. Universidade do Porto. 2010